Architecture basically refers to the practice of designing, styling or laying out carefully the complex structure, framework, anatomy or composition and organization of something. Three-tier architecture or n-tier architecture as it is commonly known within software engineering circles refers to a client-server architecture that logically separates presentation, data processing and data or information management. It provides developers with a relatively flexible platform that enables them to create and recreate reusable applications. It also saves developers time and energy by allowing them to modify or add layers instead or reconstructing, reworking or recreating the entire application. In effect therefore, it allows the developer, an opportunity to work on one particular tier at a time without affecting the rest of the other tiers. These tiers include: The Presentation Tier; the Logic Tire; and Data Tier.
Despite being costly and manifestly complex, the n-tier architecture is by far and admittedly so, the most exceptional and sophisticated user command execution software-architecture pattern in comparison to the 1 Tier, 2 Tier and 3 Tier patterns which in contrast are relatively slow. It is flexible and allows independent upgrading or replacement of a tire in response to the changing technology without impacting the operations of the other tiers. For instance, a change in the operating system in the presentation tier would only affect user-interface codes and shall not affect the logic tire or the interpretation and logical analysis of commands. Further, it off-loads business logic from the database server and client, a factor which improves performance. It also automatically changes to business logic and such changes require only new application server software to be installed. It also has a better load balancing as well and it is easier to replace other tiers without impacting the operations of the others.
Presentation Tier:
This is the top-most level tire and refers to the platform where the user gets to interact with the machine. It takes the commands given by the user and sends them to the second level logic tire. Though the language with which it takes command is pretty simple and user defined, the presentation tire transforms or translates the command into a language the machine understands and thus facilitating easier, quicker and effective issuance and execution of any such commands. It serves as the input and output tier.
The Logic Tier:
The logic tier receives input from the presentation tier and does all the logical analysis and interpretation of the command before the same can be sent to the data tier for execution. It basically serves to control an application’s functionality by performing detailed and in-depth analysis and processing of the data fed in. It acts as the intermediary between the presentation tire which directly interacts with the user and the data tier. It basically preforms and executes the most important and delicate as well as complex of commands fed into the system. Without it, the user may not get logical, coherent and accurate results from the commands they issue and as explained herein before, the process in such circumstances would be relatively slow and annoyingly cumbersome to the user.
Data Tier
This is the popular third tier which receives execution commands from the logic tier. It comprises database servers and primarily stores and retrieves information. It is relatively noteworthy that this tier, unlike the other two, is neutral and as such is independent. This in effect improves scalability and performance of the parttern. Also commonly known as the data services layer, it interacts with the persistent or commonly keyed in data to give results. The information retrieved is transferred to the logic tier that eventually does the actual execution of the initial command before eventually transmitting the results to the user vide the presentation tier in a language they understand. From the diagrammatic presentation below, the data tier has in store the numbers and figures the user intends to find the sum of. It receives the command from the logic tier and retrieves the figures. It then transfers the same to the logic tier to do the calculation before eventually relaying the answer to the user. Whereas the details on the presentation interface show 3+3 at the beginning, the same at the end of the command would reflect 3+3=6.
DIAGRAMATIC PRESENTATION
Presentation Tier: Is the uppermost tire in the user interface and servers to breakdown tasks and results into a language the user is familiar with. It is also referred to as the interactive tier.
Logic Tier: Serves the purpose of receiving and executing commands from the user at the presentation tier. It also makes logical evaluations and performs various tasks including calculations. It also serves as an intermediary between the Presentation tire and data tire by moving and processing data between the two tiers.
Data Tire: This is the tire where the information is stored and retrieved on command. It acts as the filing system of the entire process. Once retrieved, the information is transferred to the Logic tire where it is interpreted and presented in a language the user understands.
References
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